1. Field of the Invention
This invention relates, generally, to clamps. More particularly, it relates to a clamp for holding solar collectors or similar items to a flat or sloped roof covered by shingles, tin, barrel tile, or other type of roof covering.
2. Description of the Prior Art
A roof-mounted solar collector often includes a pair of parallel main pipes, usually called the top header and the bottom header, that are interconnected by a plurality of smaller pipes disposed at right angles to the top and bottom headers. On a sloped roof, the top header is the header at the higher of the two elevations. Water from a swimming pool is pumped to the bottom header from which it flows into the smaller pipes where heat from the sun is absorbed before the water flows into the top header. The heated water flowing through the top header is returned to the pool.
A clamp known as a Z-bar is currently in use as the means for mounting a header to the roof of a house. The name is derived from a side elevational view of the clamp. A Z-bar has a first flat part that is secured to the roof and a second flat part that overlies the header. More particularly, the bottom stroke of a “Z” represents the first flat part secured to the roof and the top stroke of a “Z” represents the second flat part that overlies the header. The diagonal part of the “Z” interconnects the two flat parts.
The Z-bar clamp is acceptable to at least some extent in connection with roofs, both sloped and flat, covered by shingles, tin, or the like. It is not completely satisfactory on such roofs, however, for several reasons. First of all, the first flat part of a Z-bar that is secured to a roof as mentioned above is pre-drilled to accept the fastening means that secure the Z-bar to the roof. Specifically, a pair of screw-receiving apertures are formed in said first flat part. If there is no rafter or other support beneath one or both of the apertures, the resulting fastening can be unsatisfactory.
Secondly, since a header is typically formed by joining together a pair of longitudinally aligned pipes, a pipe-joining clamp must be positioned where the two pipes abut one another, and the pipe-joining clamp must be attached to the Z-bar. Thus, the position of the pipe-joining clamp is controlled by the position of the abutting pipes and the position of the pipe-joining clamp determines the position of the Z-bar and hence of the fastening apertures. If the apertures are not aligned with a rafter or other support element below the roof, the fastening of the header will be unsatisfactory for the reason stated above.
Since the position of the pipe-joining clamp determines the position of the Z-bar and hence of the fastening means, the person designing the solar collection installation is restricted and an optimal installation where all fastening members are secured in rafters or other support members often cannot be achieved. Other clamps as well as straps must be installed exactly where spacing occurs between panels or sets of tubes. Attaching such clamps to rafters or other optimal spots on the roof, therefore, is virtually impossible.
The current art is even less satisfactory on barrel tile roofs because each barrel tile presents a convexity. The first flat part of the Z-bar should therefore be attached to each barrel tile at the exact peak or zenith of each tile. There can be only one attachment point at each barrel tile and each attachment point is spaced from its contiguous attachment points by the spacing between contiguous peaks. The pre-drilled apertures of the Z-bar are unlikely to match the peaks of the tiles, with the result that one of the fastening means can be placed at the peak of a tile, but the adjacent fastening means is unlikely to match a peak. The resulting clamping effect is less than optimal.
Other clamps and straps have the same detriment since they must attach to the roof exactly where spacing occurs between panels or sets of tubes.
Z-bars are also unsatisfactory because they space the header slightly above the roof, but not by much. Thus, when a header expands under heat, there is very little room for the header to expand in the vertical or transverse direction. Similarly, the design of a Z-bar does not accommodate longitudinal expansion of a header. When the header expands or contracts due to temperature fluctuations, the fastening screws are stressed and become loose and may even pop out under the force of the expansion or contraction. This of course unacceptably leads to a roof with leaks. Moreover, the collector itself may break under the strain.
This inadequate clearance between a header and roof provided by a Z-bar also leads to abrasion of the roof as the header expands and contracts. Straps and other clamps do not lift the header off the roof at all and lead to severe abrasion of the roof and the header.
Z-bars are even less satisfactory on barrel tile roofs because each barrel tile presents a convexity. The first flat part of the Z-bar should therefore be attached to each barrel tile at the exact peak or zenith of each tile. There can be only one attachment point at each barrel tile and each attachment point is spaced from its contiguous attachment points by the spacing between contiguous peaks. The pre-drilled apertures of the Z-bar are unlikely to match the peaks of the tiles, with the result that one of fastening means can be placed at the peak of a tile, but the adjacent fastening means is unlikely to match a peak. The resulting clamping effect is less than optimal.
Z-bars and other clamps are also unsatisfactory because they limit the header movement that results from heat driven expansion and contraction of the collector in the lateral and longitudinal directions. When the header expands or contracts due to temperature fluctuations, the fastening screws are stressed and become loose and may even pop out under the force of the expansion or contraction. This of course unacceptably leads to a roof with leaks. Moreover, the collector itself may break under the strain.
An improved clamping means for flat or sloped roofs covered by shingles, tin, barrel tile, and the like is therefore required.
More particularly, a clamping means is needed that can be placed at any position along the length of a header, without limitation to the vicinity of the location where two pipes join to form a header. Such a clamp, unlike a Z-bar, could always be secured to a rafter or other underlying support member. It could also be placed, in barrel tile applications, directly at the apex of a barrel tile in cooperation with another clamp also positioned on the apex of another barrel tile.
A clamp is also needed that provides additional vertical clearance space between a header and a roof to prevent roof abrasion by movement of the header and to accommodate heat-related expansion and contraction of the header. A clamp that allows enhanced longitudinal expansion of the header is also desirable. If a clamp allows heat-related expansion and contraction, both in a vertical or transverse direction and in a longitudinal direction, then the screws that hold it down will not become stressed and will not become loose. Nor will the collector structure itself break.
The needed clamp should be positionable at any preselected point along the extent of a header, and thus at any preselected point on the roof, thereby allowing the designer of a solar collector installation maximum flexibility.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how such need could be fulfilled.